Valve timing control apparatus and internal combustion engine

ABSTRACT

A valve timing control apparatus includes a driving rotary member driven by an engine, and a driven rotary member to drive a camshaft of the engine. The driven member is rotatable relative to the driving rotary member. A first movable member is provided in one of the rotary members, and arranged to move forwards and backwards. A second movable member is provided in the other of the rotary members, and arranged to move forwards and backwards. The first and second movable members are arranged to limit a relative rotation between the driving rotary member and the driven rotary member when both the first movable member and the second movable member are moved forwards, and to allow the relative rotation when at least one of the first and second movable members is moved backwards.

BACKGROUND OF THE INVENTION

The present invention relates to an internal combustion engine equipped with a valve timing control apparatus and/or a valve timing control apparatus for controlling a valve timing of an internal combustion engine such as opening and closing timings of intake or exhaust valve.

A published Japanese Patent Specification Publication No. 2000-002104 shows a valve timing control apparatus (VTC) of a vane type including a rotary unit of a timing sprocket member and a vane member, and a lock mechanism including a lock pin to limit a relative rotation between the timing sprocket member and vane member. The lock pin includes a small diameter pressure receiving section and a large diameter pressure receiving portion.

SUMMARY OF THE INVENTION

In the valve timing control apparatus of this document, the lock pin receives tow different hydraulic pressures at the two different pressure receiving portions. Therefore, it is difficult to minutely adjust the spring force of a spring biasing the lock pin to the lock position.

According to one aspect of the present invention, a valve timing control apparatus for an internal combustion engine, comprises: a driving rotary member adapted to be driven by the engine; a driven rotary member arranged to rotate relative to the driving rotary member and adapted to rotate a camshaft of the engine; a first movable member provided in a first rotary member, and arranged to move forwards and backwards, the first rotary member being one of the driving rotary member and the driven rotary member; and a second movable member provided in a second rotary member and arranged to move forwards and backwards, the second rotary member being the other of the driving rotary member and the driven rotary member. The first and second movable members are arranged to limit a relative rotation between the driving rotary member and the driven rotary member when both the first movable member and the second movable member are moved forwards, and to allow the relative rotation between the driving rotary member and the driven rotary member when at least one of the first and second movable members is moved backwards.

According to another aspect of the invention, an internal combustion engine comprises: a crankshaft; a camshaft; a valve timing control rotary mechanism including, a driving rotary member driven by the crankshaft of the engine, and a driven rotary member which is arranged to be driven by the driving rotary member and to drive the camshaft, and which is arranged to rotate relative to the driving rotary member to alter a rotational position of the driven rotary member relative to the driving rotary member; and a lock mechanism including, a first movable member mounted in the driven rotary member and arranged to move forwards toward the driving rotary member and backwards away from the driving rotary member, and a second movable member mounted in the driving rotary member and arranged to move forwards toward the driven rotary member and backwards away from the driven rotary member. The second movable member is arranged to abut against the first movable member and thereby to limit a relative rotation between the driving rotary member and the driven rotary member when both the first movable member and the second movable member are moved forwards.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view taken across a line F1-F1 in FIG. 2, for showing an internal combustion engine provided with a valve timing control system according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken across a line F2-F2 in FIG. 1, for showing the valve timing control system of FIG. 1.

FIG. 3A is a sectional view taken across the line F2-F2 in FIG. 1, for showing the valve timing control system of FIG. 1 at the time of a start of the engine. FIG. 3B is an enlarged view of a part of FIG. 3A.

FIG. 4A is a sectional view taken across the line F2-F2 in FIG. 1, for showing the valve timing control system of FIG. 1 at the time of an idling operation of the engine. FIG. 4B is an enlarged view of a part of FIG. 4A.

FIG. 5A is a sectional view taken across the line F2-F2 in FIG. 1, for showing the valve timing control system of FIG. 1 at the time of an operation in a low speed, low load region of the engine. FIG. 5B is an enlarged view of a part of FIG. 5A.

FIG. 6A is a sectional view taken across the line F2-F2 in FIG. 1, for showing the valve timing control system of FIG. 1 at the time of an operation in a medium speed, medium load region of the engine. FIG. 6B is an enlarged view of a part of FIG. 6A.

FIG. 7 is a partial cutaway view showing a valve timing control apparatus according to a second embodiment of the present invention.

FIG. 8 is a partial cutaway view for illustrating operation of the valve timing control apparatus of FIG. 7 with a vane member at a most retarded position.

FIG. 9 is a partial cutaway view for illustrating operation of the valve timing control apparatus of FIG. 7 with the vane member at an intermediate rotational position.

FIG. 10 is a partial cutaway view for illustrating operation of the valve timing control apparatus of FIG. 7 with the vane member at a most advanced position.

FIG. 11 is a schematic view showing a valve timing control apparatus including a hydraulic circuit according to a third embodiment of the present invention.

FIG. 12 is a partial cutaway view showing a valve timing control apparatus according to a fourth embodiment of the present invention.

FIG. 13 is a partial cutaway view for illustrating operation of the valve timing control apparatus of FIG. 12 with a vane member at the most retarded position.

FIG. 14 is a partial cutaway view for illustrating operation of the valve timing control apparatus of FIG. 12 with the vane member at the intermediate rotational position.

FIG. 15 is a partial cutaway view for illustrating operation of the valve timing control apparatus of FIG. 12 with the vane member at the most advanced position.

FIG. 16 is a sectional view taken across a line F16-F16 shown in FIG. 17, showing a valve timing control apparatus according to a fifth embodiment of the present invention.

FIG. 17 is a sectional view taken across a line F17-F17 shown in FIG. 16.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an internal combustion engine equipped with a valve timing control apparatus or system according to a first embodiment of the present invention. FIG. 2 shows the valve timing control apparatus in section taken across a line F2-F2 in FIG. 1 whereas FIG. 1 is a sectional view taken across a line F1-F1 shown in FIG. 2. In this embodiment, the present invention is applied to an intake valve's side. However, it is possible to apply the invention to an exhaust valve's side.

A timing sprocket member 1 is a driving rotary member driven through a timing chain 61 by a crankshaft 62 of the internal combustion engine. A camshaft 2 is rotatable relative to sprocket member 1. A vane member 3 is a driven rotary member which is fixed at an end of camshaft 2 so that they rotate as a unit, and which is encased rotatably in sprocket member 1. A hydraulic circuit 4 is a component of a control section to rotate vane member 3 in a forward rotational direction and a reverse rotational direction in sprocket member 1 by the action of oil pressure.

Timing sprocket member 1 includes a sprocket housing 5, a front cover 6 and a rear cover 7 which are joined together by fastening devices which, in this example, are three small-diameter bolts 8. Housing 5 is a hollow cylindrical member extending axially from a front open end to a rear open end. Housing 5 includes a toothed portion 5 a formed integrally on the periphery of housing 5, and arranged to engage in links of timing chain 61. Vane member 3 is enclosed rotatably in housing 5. Front cover 6 is in the form of a circular disk, and arranged to close the front open end of housing 5. Rear cover 7 is in the form of an approximately circular disk and arranged to close the rear open end of housing 5. Front cover 6, housing 5 and rear cover 7 are joined together to form a housing encasing the vane member 3, by the before-mentioned bolts 8 extending in the axial direction of camshaft 2.

Housing 5 is approximately in the form of a hollow cylinder open at both ends. Housing 5 includes a plurality of partitions 10 projecting radially inwards from an inside circumferential wall surface of cylindrical housing 5. Projecting partitions 10 serve as housing shoes. In this example, the number of partitions 10 is three, and these three partitions 10 are arranged at angular intervals of approximately 120°, circumferentially in the inside circumference of housing 5. Each partition 10 extends axially from the front open end to the rear open end of housing 5, and has an approximately trapezoidal cross section as viewed in FIG. 2. In this example, housing 5 includes a front end surface which is substantially flat and which is joined with front cover 6, and a rear end surface which is substantially flat and which is joined with rear cover 7. Each partition 10 of this example includes a front end surface which is flat, and flush and continuous with the flat front end surface of housing 5, and a rear end surface which is flat, and flush and continuous with the flat rear end surface of housing 5. A bolt hole 11 is formed approximately at the center of each partition 10. Each bolt hole 11 passes axially through one of partitions 10, and receives one of the axially extending bolts 8. Each partition 10 includes an inner end surface which is sloping in conformity with the outer shape of a later-mentioned vane rotor (14) of vane member 3. A retaining groove 11 extends axially in the form of cutout in the inner end surface of each partition at a higher position. A U-shaped seal member 12 is fit in each retaining groove 11, and urged radially inwards by a leaf spring (not shown) fit in the retaining groove 11.

Front cover 6 includes a center bolt hole 6 a having a relatively large inside diameter; and three bolt holes 6 b each receiving one of the axially extending bolts 8. These three bolt holes 6 b are arranged around the center bolt hole 6 a.

Rear cover 7 includes a center bearing hole 7 a supporting rotatably a front end portion 2 a of camshaft 2; and three threaded holes 7 b into which three bolts 8 are screwed, respectively.

Camshaft 2 is rotatably supported through a cam bearing 13 on an upper portion of a cylinder head S of the engine. Camshaft 2 includes one or more cams formed integrally on the outer circumference of camshaft 2 at predetermined positions. Each cam is arranged to open an intake valve of the engine through a valve lifter.

Vane member 3 of this example is a jointless single member made of sintered alloy. Vane member 3 includes a central vane rotor 14 and a plurality of vanes 15 projecting radially outwards. In this example, the number of vanes 15 is three, and these three vanes 15 are arranged at angular intervals of approximately 120° circumferentially around vane rotor 14. Vane rotor 14 is annular and includes a center bolt hole 14 a at the center. Vane member 3 is fixed to a front end 2 a of camshaft 2 by a cam bolt 16 extending axially through the center bolt hole 14 a.

The three vanes 15 are approximately rectangular, and these vanes 15 are unequal in circumferential width L measured in the circumferential direction around a common center axis of a rotary mechanism composed of vane member 3 and timing sprocket 1. A first one of the three vanes 15 is a smaller vane having a smallest circumferential width L1, a second one is a medium vane having an intermediate circumferential width L2 greater than L1, and a third one is a larger vane having a largest circumferential width L3 greater than L2. These vanes are formed so that a weight balance is attained as a whole of the vane member 3. The three vanes 15 of vane member 3 and the three partitions 10 of timing sprocket member 1 are arranged alternately in the circumferential direction around the center axis, as shown in FIG. 2. Namely, each vane 15 is located circumferentially between adjacent two of the partitions 10. Each vane 15 includes a retaining groove receiving a U-shaped seal member 16 in sliding contact with the inside cylindrical surface of housing 5, and a leaf spring (not shown) for urging the seal member 16 radially outward and thereby pressing the seal member 16 to the inside cylindrical surface of housing 5.

Each vane 15 includes a first side surface facing in the rotational direction of vane member 3 and a second side surface facing in a rotational direction opposite to the rotational direction. In the case of the smaller vane having the smallest width L1, the retaining groove is formed at a middle of an outer end of the vane. In the medium vane 15 having the intermediate width L2, the retaining groove is formed in the outer end of the vane at a position closer to the first side surface of the vane. In the greater vane 15 having the greater width L3, the retaining groove is formed in the outer end of the vane at a position closer to the second side surface of the vane.

An advance fluid pressure chamber 17 and a retard fluid pressure chamber 18 are formed on both sides of each vane 15. Advance pressure chamber 17 is defined between the second side surface of each vane 15 and the adjacent partition 10 to which the second side surface of the vane faces. Retard pressure chamber 18 is defined between the first side surface of each vane 15 and the adjacent partition 10 to which the first side surface of the vane faces.

Hydraulic circuit 4 includes a first fluid pressure passage or advance fluid pressure passage 19 leading to the advance chambers 17 to supply and drain an advance fluid pressure of an operating oil to and from advance chambers 17; a second fluid pressure passage or retard fluid pressure passage 20 leading to the retard chambers 18 to supply and drain a retard fluid pressure of the operating oil to and from retard chambers 18, and a directional control valve or selector valve 23 connecting the advance pressure passage 17 and retard pressure passage 18 selectively with a supply passage 21 and a drain passage 22. In this example, control valve 23 is a solenoid valve. A fluid pump 25 is connected with supply passage 21, and arranged to draw the hydraulic operating fluid or oil from an oil pan 24 of the engine, and to force the fluid into supply passage 21. Directional control valve 23 of this example is a one-way type pump. Drain passage 22 is connected to oil pan 24, and arranged to drain the fluid to oil pan 24. At least one of directional control valve 23 and pump 25 can serve as an actuating device for forcing one of first and second movable (lock) members backwards, as mentioned later.

Advance fluid pressure passage 19 includes a first passage section 19 a, a second passage section 19 b serving as a pressure chamber, and three branch passages (not shown) connecting second passage section 19 b, respectively, with the three advance chambers 17. Passage section 19 a extends in cylinder head S, and further extends axially in camshaft 2, to second passage section 19 b. Second passage section 19 b is formed by vane member 3, at a position between vane rotor 14 and the front end of camshaft 2. The three branch passages are formed in vane member 3 and extend radially in vane member 3.

Retard fluid pressure passage 20 includes a first passage section 20 a extending in cylinder head S and axially in camshaft 2, and a second passage section 20 b formed in vane rotor 14. Second passage section 20 b is approximately L-shaped, and connected with each retard pressure chamber 18.

Directional control valve 45 of this example is a solenoid valve having four ports and two positions. A valve element inside the control valve 45 is arranged to alter the connection between the passages 19 and 20 and the supply and drain passages 21 and 22.

A controller 26 produces a control signal, and controls the solenoid control valve 45 by sending the control signal to the valve 45. A sensor section 63 collects input information on operating conditions of the engine and a vehicle in which this timing control apparatus is installed. Input information is supplied to controller 26. The sensor section 63 of this example includes a crank angle sensor 64 for sensing a speed of the engine, an air flowmeter 65 for sensing an intake air quantity of the engine, a cam angle sensor 66 and an input device 67, such as an ignition switch or a vehicle main switch, to sense a start of the engine. Controller 26 determines a current operating state from the signals from crank angle sensor 64 and air flowmeter 65, and further determines a relative rotational position between sprocket member 1 and camshaft 2.

Vane member 3, advance and retard chambers 17 and 18 and hydraulic circuit 4 form a varying mechanism varying the relative rotational position between the driving rotary member such as sprocket member 1 and the driven rotary member such as vane member 3. Sprocket member 1 and vane member 3 form a valve timing control rotary mechanism. A control section for controlling the relative displacement between the driving rotary member such as sprocket member 1 and the driven rotary member such as vane member 3 may include at least one of the hydraulic circuit 4 and controller 26. The control section may further include the sensor section 63.

A lock mechanism is a mechanism to prevent and allow the relative rotation between the driving rotary member that is sprocket member 1 in this example and the driven rotary member that is vane member 3 in this example. The lock mechanism is provided between the sprocket member 1 and vane member 3. In this example, the lock mechanism is formed between housing 5 and a portion of vane rotor 14 adjacent to the smaller vane 15 having the circumferential width L1. The lock mechanism includes a first lock unit or mechanism 27 provided in vane rotor 14 of vane member 3 and a second lock unit or mechanism 28 provided in housing 5 of sprocket member 3.

First lock unit or mechanism 27 (which is a driven-side lock unit in this example), as shown in FIGS. 1˜3, includes a first (or driven-side) lock member 30 which can serve as one of first and second movable members. First lock member 30 is slidably received in a first slide hole 29 formed in vane member 3. In this example, first slide hole 29 is formed in a boss portion 14 b formed in vane rotor 14. Boss portion 14 b is located on an advance chamber's side of the smaller vane 15 having the smallest width L1. As shown in FIG. 2, boss portion 14 b is located circumferentially between the smaller vane 15 and the adjacent partition 10 defining and bounding the advance chamber 17 for the smaller vane 15. First slide hole 29 extends radially in vane member 3, and first lock member 30 is movable radially in the radially extending first slide hole 29. First lock member 30 is a cup-shaped member in the form of a hollow cylinder having one end closed. First lock member 30 includes a circumferential wall extending in a radial outward direction of vane member 3 from an open inner end to an outer end, and a forward end portion 30 a closing the outer end of the circumferential wall.

First lock unit 27 on the driven side further includes a first (or driven-side) spring 31 which can serve as one of first and second bias members. First spring 31 is disposed between vane member 3 and first lock member 30 and arranged to bias or urge first lock member 30 forwards toward the sprocket member 1 in a radial outward direction which may not be an exact direction of a radius emanating from the center axis of vane member 3. In this example, first spring 31 is a coil spring disposed between the inside surface of the forward end portion 30 a of first lock member 30 and the bottom of first slide hole 29 formed in boss portion 14 b of vane member 3. An outer portion of first spring 31 is inserted into the inside of first lock member 30 and enclosed by the circumferential wall of first lock member 30.

First slide hole 29 of this example extends radially from the bottom to an outer end opening into the advance fluid pressure chamber 17 for the vane 15 of the smallest width L1. The depth of first slide hole 29 is longer than the length of first lock member 30.

The forward end portion 30 a of first lock member 30 is exposed to the advance fluid pressure in the advance chamber 17, so that the advance fluid pressure is applied to the forward end portion 30 a so as to force the first lock member 30 backwards toward the bottom of first slide hole 29, in a radial inward direction away from the sprocket member 1. The forward end portion 30 a of first lock member 30 of this example has an outside convex surface which is spherical or shaped like a circular arc in section. First lock member 30 further includes an outward flange 30 b formed at the inner or backward end of the circumferential wall of first lock member 30. A hollow cylindrical stopper 35 is fixed in the first slide hole by press fitting, and arranged to limit a radial outward movement of first lock member 30 by abutting against the outward flange 30 b of first lock member 30, as shown in FIG. 3A. Therefore, stopper 35 and outward flange 30 b determines a forward limit position beyond which first movable member 30 can not be moved and projected by first spring 31.

First (or driven-side) spring 31 is set at such a spring force that first spring 31 can push the first lock member 30 forwards when the hydraulic pressure in the advance fluid pressure chamber 17 is low without the supply of the advance fluid pressure, and that first spring 31 is compressed by the advance fluid pressure in the advance fluid pressure chamber 17, to allow the first lock member 30 to be moved backwards deeper in the first slide hole 29 toward the bottom of first slide hole 29 when the hydraulic pressure in the advance fluid pressure chamber 17 becomes high by receiving the supply of the advance fluid pressure.

Second lock unit or mechanism 28 (which is a driving-side lock unit in this example), as shown in FIGS. 1˜3, includes a second (or driving-side) lock member 33 which can serve as the other of the first and second movable members. Second lock member 33 is slidably received in a second slide hole 32 formed in sprocket member 1. In this example, second slide hole 32 is formed in a boss portion 5 b formed integrally at the side of the partition 15 defining the advance chamber 17 of the vane 15 having the smallest width L1. Boss portion 5 b is located circumferentially between the smaller vane 15 and the adjacent partition 10 defining and bounding the advance chamber 17 for the smaller vane 15. Second slide hole 32 extends radially in sprocket member 1, and second lock member 33 is movable radially in the radially extending slide hole 32. Second lock member 33 is shaped approximately like a cup, and includes a circumferential wall extending in a radial inward direction of sprocket member 1, from an outer end to an inner end, and a forward end portion formed so as to close the inner end of the circumferential wall.

Second lock unit 37 on the driving side further includes a second (or driving-side) spring 34 which can serve as the other of the second and first bias members. Second spring 34 is disposed between sprocket member 1 and second lock member 33, and arranged to bias or urge second lock member 33 forwards toward the vane member 3 in a radial inward direction which may not be an exact direction of a radius converging to the center axis of vane member 3. In this example, second spring 34 is a coil spring disposed between the inside surface of the forward end portion of second lock member 33 and the bottom of second slide hole 32 formed in boss portion 5 b of sprocket member 1. An inner portion of second spring 34 is inserted into the inside of second lock member 33 and enclosed by the circumferential wall of second lock member 33.

Second slide hole 32 of this example extends radially inward from an outer open hole end to an inner open hole end. A plug or cover member 40 closes the outer open hole end of second slide hole 32, and thereby forms the bottom of second slide hole 32. Second spring 34 is disposed between plug member 40 and the forward end portion of second lock member 33. Plug member 40 of this example is a circular plate and fixed to sprocket member 1. Second slide hole 32 includes an outer large-diameter section extending from the outer hole end closed by plug member 40, toward the inner hole end of second slide hole 32; an inner small-diameter section extending from the inner hole end toward the outer hole end of second slide hole 32; and an annular step shoulder surface 32 a formed between the large-diameter section and the small-diameter section. Annular step shoulder surface 32 a faces approximately in the radial outward direction toward the outer hole end.

Second lock member 33 includes an outer large-diameter section slidably received in the outer large-diameter portion of second slide hole 32; an inner small-diameter section slidably received in the inner small-diameter section of second slide hole 32; and an annular step shoulder surface 33 a formed between the large-diameter section and the small-diameter section of second lock member 33. The inner small-diameter section of second lock member 33 is greater in diameter than the forward end portion 30 a of first lock member 30. Annular shoulder surface 33 a faces approximately in the radial inward direction. Annular step shoulder surface 33 a serves as a pressure receiving surface of an outward flange.

An annular pressure chamber 33 b is formed around the second lock member 33 between the annular shoulder surface 33 a and annular shoulder surface 32 a. The annular shoulder surface 33 a of second lock member 33 is arranged to receive the pressure in the annular pressure chamber 33 b. Sprocket member 1 is formed with a communication passage 36 for introducing one of the advance fluid pressure and the retard fluid pressure to the annular pressure chamber 33 b to apply the hydraulic pressure to second lock member 33 to move the second lock member 33 backwards. In this example, communication passage 36 extends from a first end opening in the retard fluid pressure chamber 18, through the vane 15, to a second end 36 a opening into the annular pressure chamber 33, as shown in FIG. 2. Therefore, second lock member 33 is arranged to move backwards toward the bottom of second slide hole 32 in the radial outward direction by the application of the retard fluid pressure introduced from the retard fluid pressure chamber 18 into the annular pressure chamber 33 b. The annular step shoulder surface 32 a faces approximately in the radial outward direction, and functions to limit a radial inward movement of second lock member 33 by abutting on the annular step shoulder surface 33 a of second lock member 33.

Second (or driving-side) spring 34 is set at such a spring force that second spring 34 can push the second lock member 33 forwards when the hydraulic pressure in the retard fluid pressure chamber 18 is low without supply of the retard fluid pressure, and that second spring 34 is compressed by the retard fluid pressure in the retard fluid pressure chamber 18, to allow the second lock member 33 to be moved backwards deeper in the second slide hole 32 toward the bottom of second slide hole 32 when the hydraulic pressure in the annular pressure chamber 33 b becomes high by receiving the supply of the retard fluid pressure. The spring force of second spring 34 is set greater than the spring force of first spring 31.

The forward end portion of second lock member 33 is formed with a (lock) recess 37. On the other hand, the forward end portion of first lock member 30 is in the form of a (lock) projection which can engage in the recess 37 of second lock member 33. The forward end portion of second lock member 33 includes an end wall forming the bottom of recess 37, and separating the inside cavity of the circumferential wall of second lock member 33 and the inside of recess 37. This end wall is formed with a through hole 38 extending through this end wall and thereby fluidly connecting the inside of recess 37 and the inside of the circumferential wall or the inside of the second slide hole 32. The inside diameter of recess 37 (which is a circular recess in this example) is set greater than the outside diameter of the forward end portion (projection) 30 a of first lock member 30. Therefore, the forward end portion 30 a of first lock member 30 is loosely fit in recess 37 of second lock member 33 in a lock state in which the forward end portion 30 a of first lock member 30 is received in recess 37 of second lock member 33 as shown in FIG. 2 and FIGS. 3A and 3B.

The forward end portion of second lock member 33 is further formed with a guide surface 39 serving as guide means for guiding first and second lock members 30 and 33 into the lock state in which the projection (30 a) of first lock member 30 is fit loosely in the recess 37 of second lock member 33. In this example, the guide surface 39 is in the form of an annular tapered surface or conical surface.

In the state in which no hydraulic pressures are supplied to the advance and retard fluid pressure chambers 17 and 18 for example at the time of engine stoppage, the vane member 3 is set at a predetermined (lockable) rotational position (which is the most retarded position in this example) as shown in FIGS. 1, 2, 3A and 3B. In this state, the vane 15 having the greatest circumferential width L3 abuts against the adjacent partition 10 of sprocket member 1 in the retard rotational direction. In this state, the vane 15 of the medium width L2 is spaced by a minute clearance C from the adjacent partition 10 in the retard rotational direction. The vane 15 having the medium width L2 does not abut on the adjacent partition 10. Similarly, the vane 15 of the smallest width L1 is spaced by a minute clearance C from the adjacent partition 10 without abutting on the partition 10. When vane member 3 is located at this predetermined (lockable or most retarded) position relative to sprocket member 1, the forward end portion 30 a of first lock member 30 can enter the recess 37 of second lock member 33, and the first and second lock members 30 and 33 can shift into the lock state.

The minute clearance C of each of these vanes 15 (of the medium and smallest widths) is determined in accordance with the average torque, sliding friction and the size of the vane 15. These minute clearances C are effective for preventing adhesion of the vanes to partitions 10 and thereby improving the response speed of vane rotation. It is possible set a clearance for each of all the three vanes 15 so that, in the predetermined lockable rotational position, each of all the vanes is set apart from the corresponding partition 10.

The thus-constructed valve timing control apparatus is operated as follows: At the time of start of the engine, controller 26 produces the control signal, and solenoid directional control valve 23 is set to the position to connect the supply passage 21 with second (retard) fluid passage 20 and connect the drain passage 22 with first (advance) fluid passage 19. Therefore, the fluid pressure produced by pump 25 is supplied through second passage 20 to retard chambers 18 whereas the advance chambers 17 are held in the low pressure state with no supply of hydraulic pressure as in the engine stop state.

Therefore, first lock member 30 projects forwards in the radial outward direction by the force of first spring 31 until the forward limit position is reached by abutment of flange 30 b against the inner end of stopper 35. On the other hand, second lock member 33 projects forwards in the radial inward direction by the force of second spring 34 until the forward limit position is reached by abutment of flange 33 a against shoulder surface 32 a since the hydraulic pressure inside the retard chambers 18 is not increased sufficiently. Therefore, the forward end portion 30 a of first lock member 30 is engaged in the recess 37 of second lock member 33. In this state, the outside circumferential surface of forward end portion 30 a of first lock member 30 abuts against the inner side surface of lock recess 37 of second lock member 33, and thereby prevent the relative rotation between vane member 3 and sprocket member 1.

Therefore, as shown in FIG. 2 and FIGS. 3A and 3B, the wide vane having the greatest width L3 abuts against the adjacent partition 10 on the advance chamber's side, and the first and second lock members 30 and 33 are put in the lock state to prevent the relative rotation between vane member 3 and sprocket member 1

In this state, the relative rotational angle of camshaft 2 relative to timing sprocket member 1 is held on the retard side, and the opening and closing timings of the intake valve are controlled to the retard side. By so doing, this valve timing control system can improve the combustion efficiency by utilizing inertial intake air, and improve the engine cranking performance. Moreover, the lock mechanism of first and second lock members 30 and 33 in the lock state can prevent vibrations or flapping of vane member 3 due to alternating torque of camshaft 2 between the positive and negative sides in the engine starting operation.

In an idling operation, the solenoid directional control valve 23 is held in the existing state and the hydraulic pressure in retard fluid pressure chambers 18 becomes higher. When the hydraulic pressure in retard chambers 18 becomes higher than the level of the alternating torque, the flange portion 33 a of second lock member is acted upon by the fluid pressure introduced into the pressure chamber 33 b through communication passage 36; and the second lock member 33 compresses second spring 34 and moves backwards, so that the recess 37 of second lock member 33 moves away from the forward end portion 30 a of first lock member 30, as shown in FIGS. 4A and 4B. Thus, first and second lock members 30 and 33 are put in an unlock state allowing the relative rotation of vane member 3. However, the hydraulic pressure in retard chambers 18 is high, and the vane member 3 is held in the most retarded position shown in FIGS. 4A and 4B (this state is called a standby state).

When the vehicle starts moving, and the engine operating point enters a predetermined low speed, low load region, the controller 26 sends the control signal and switches the directional control valve 23 to the state connecting the supply passage 21 with first (advance) passage 19, and the drain passage 22 with second (retard) passage 20. Therefore, the fluid is returned from retard chambers 18 through second passage 20 and drain passage 22 to oil pan 24, and the hydraulic pressure in retard chambers 18 becomes low. On the other hand, the hydraulic pressure in advance chambers 17 becomes high by the supply of the fluid pressure.

Therefore, second lock member 33 moves forwards by the force of second spring 34 to the forward limit position determined by abutment between flange surface 33 a and step surface S32 a, as shown in FIGS. 5A and 5B. On the other hand, first lock member 30 moves backwards by the hydraulic pressure in the advance chamber 17 against the first spring 31 into the first slide hole 29. Therefore, vane member 3 rotates in the clockwise direction from the rotational position shown in FIGS. 4A and 4B, to the rotational position shown in FIGS. 5A and 5B, intermediate between the most retarded position and the most advanced position.

When the engine operating point shifts into a medium speed, medium load region, and the supply pressure to advance chambers 17 becomes high, the vane member 3 is further rotated in the advance direction (that is, the clockwise direction as viewed in FIGS. 6A and 6B) until the greater vane 15 abuts against the adjacent partition 15 on the retard chamber's side as shown in FIG. 6A and the most advanced position shown in FIGS. 6A and 6B is reached by vane member 3. Therefore, camshaft 2 is rotated relative to timing sprocket member 1 in the advance direction, and the opening and closing timings of the intake valve are controlled to the advance side. Therefore, the valve timing control system can decrease the pumping loss of the engine and thereby improve the engine output.

When the engine operating point further shifts into a high speed region, the controller 26 switches the solenoid valve 23 to the state connecting the supply passage 21 with second passage 20, and the drain passage 22 with first passage 19 as in the idling operation. By so doing, controller 26 decreases the hydraulic pressure in advance chambers 17 and increases the hydraulic pressure in retard chambers 18. Therefore, vane member 3 is returned in the counterclockwise direction to the most retarded position shown in FIG. 4A, and the camshaft 2 is rotated in the retard direction relative to timing sprocket member 1, so that the opening and closing timings of the intake valve are controlled to the retard side. Thus, the valve timing control system can improve the intake charging efficiency and improve the engine output.

In this case, first lock member 30 is projected forwards by the force of first spring 31. However, second lock member 33 is withdrawn backwards in second slide hole 32 by the force of the retard fluid pressure in retard chambers 18 introduced into the annular pressure chamber 33 b through communication passage 36, as shown in FIGS. 4A and 4B. First and second lock members 30 and 33 are out of the lock state.

In the stop state of the engine, the vane member 3 is restored to the most retarded position shown in FIGS. 2 and 3A by the idling operation before the stoppage of the engine. That is, the vane member 3 returns to the most retarded position while fluctuating by the effect of alternating torque. On the other hand, with a decrease in the hydraulic pressure in retard chambers 18, the second lock member 33 is projected forward until the forward end portion 30 a of first lock member 30 engages in the recess 37 of second lock member 33.

If the engine is stopped by an engine stall without experiencing the idling operation, the vane member 3 is rotated by the effect of the alternating torque to the most retarded position, and the first lock member 30 engages into the lock recess 37 of second lock member 33 automatically.

At the same time with the engine stall, the oil pump 25 is stopped, and stops the supply of hydraulic pressure to the advance and retard chambers. Therefore, the first and second lock members 30 and 33 are both projected forwards by first and second springs 31 and 34, respectively. When the vane member 3 is rotated from the position shown in FIG. 6A toward the position shown in FIG. 4A by the action of the alternating torque, the first lock member 10 remaining in the projected position collides against the second lock member 33 in the projected position. In this case, the forward end portion 30 a of first lock member 30 abuts against the annular tapered guide surface 39, and moves backwards gradually by being pushed by the guide surface 39 against the force of first spring 31 until the forward end portion 30 a of first lock member 30 enters the lock recess 37 of second lock member 37.

Therefore, at the time of a restart of the engine, the vane member 3 is locked against rotation relative to sprocket member 1, and the engine can be started smoothly as in the normal engine starting operation.

By controlling the supply and drainage of the hydraulic pressure to and from the advance and retard chambers 17 and 18 in accordance with the engine operating conditions, this valve timing control system can hold the vane member 3 at a desired intermediate rotational position as shown in FIG. 5A.

Thus, in addition to the valve timing control mechanism (1, 3 etc.) capable of controlling the valve timing by controlling the hydraulic pressures in advance and retard chambers 17 and 18; the valve timing control system according to this embodiment has the lock mechanism including the first and second lock members 30 and 33 which are arranged to confront each other and to move toward and away from each; and the first and second springs 31 and 34 for urging the first and second lock members forwards toward each other. Therefore, it is possible to select and set the urging forces and set loads of first and second springs 31 and 34 individually. Accordingly, it is possible to finely adjust various conditions such as conditions for canceling the limitation on the relative rotation between the timing sprocket member 1 and camshaft 2. Moreover, it is possible to set the areas of the pressure receiving portions 30 a and 33 a of first and second lock members 30 and 33 individually. Accordingly, more minute adjustment of various conditions is possible.

When the engine is held for a long time in the stop state, the operating oil is drained from the advance and retard chambers 17 and 18, and air flows into advance and retard chambers 17 and 18. Therefore, when the engine is started again and the oil is supplied selectively to the advance or retard chambers 17 or 18 by the pump 25, the air pressure is increased in the advance or retard chambers by the supply of the oil. By this increase of the air pressure, one of the lock members might be moved backwards away from the other, and the lock mechanism might be unlocked.

In this embodiment, however, the spring forces of first and second springs 31 and 34 and the pressure receiving area of flange surface 33 a can be set individually, and hence the adjustment is readily attainable such that the lock mechanism is not unlocked by the pressure of air, but the lock mechanism is unlocked only by the application of hydraulic oil pressure. By such adjustment, it is possible to prevent undesired noises from being produced by preventing the lock mechanism from being unlocked by the compressed air in the advance or retard chambers.

Moreover, the flexibility of the layout is increased since the unlocking conditions can be determined by the setting of the spring forces of first and second springs 31 and 34 independently from the pressure receiving area of the front end surface of first lock member 30 and the pressure receiving area of annular flange surface 33 a of second lock member 33. j0071

Even in the case of engine stall, the guide surface 39 can guide first and second lock members 30 and 33 reliably into the lock state. Even if the first and second lock members 30 and 33 fail to engage with each other in a normal engine stopping, the guide surface 39 can guide the first lock member 30 into the lock recess 37 by pushing first lock member 30 slightly backwards when vane member 3 fluctuates by the alternating torque produced during an engine cranking operation.

In the illustrated embodiment, the forward end portion 30 a of first lock member 30 includes a circumferential side wall surface which is not tapered but extends straight substantially in parallel to the longitudinal axis of first lock member 30 along which first lock member 30 can move forwards and backwards. Therefore, in the lock recess 37 of second lock member 33, the non-tapered circumferential side wall surface of the forward end portion 30 a of first lock member 30 abuts against the upright inside side wall surface of lock recess 37 of second lock member 33 with a broader contact surface area ensuring reliable engagement.

In this embodiment, as shown in FIGS. 4A and 4B as in the idling operation, the lock mechanism can be unlocked by moving only the second lock member 33 backwards by the application of hydraulic pressure in retard chambers 18. Thus, the valve timing control system can disengage the first and second lock members 30 and 33 in a stable and reliable manner.

Through hole 38 is formed in the bottom wall of lock recess 37 of second lock member 33. Through this through hole 38, the hydraulic fluid supplied to advance chambers 17 flows into the inside of second lock member 33 when second lock member 33 moves backwards and forwards. In this case, the through hole 38 serves as means for producing damping effect by the throttling, and thereby preventing flapping movement of second lock member 33.

FIGS. 7˜10 show a valve timing control apparatus according to a second embodiment of the present invention. In the second embodiment, second lock member 33 is arranged to move backwards against the spring force of second spring 34 by the effect of a centrifugal force, instead of the hydraulic pressure in retard chambers 18. The spring force of second spring 34 is set smaller than a centrifugal force of a predetermined magnitude produced in housing 5 during rotation. In this example, second spring 34 is so set that second spring 34 starts compression by the centrifugal force of housing 5 when the engine rotational speed becomes equal to or higher than an idle speed of about 900 rpm.

An air release passage 41 is formed in the circumferential wall of housing 5 of sprocket member 1. Air release passage 41 connects the annular pressure chamber 33 b with the outside, and thereby opens the inside of the annular pressure chamber 33 a to the atmosphere to allow free movement of second lock member 33 in second slide hole 32. Therefore, second lock member 33 can compress the second spring 34 and move smoothly backwards by receiving a centrifugal force of a predetermined magnitude or more during engine operation. In this embodiment, the communication passage 36 connecting the retard chamber 18 with the second slide hole 32 is eliminated.

When the centrifugal force of housing 5 is still weak after a start of the engine, the second lock member 33 is held projected forwards by second spring 34, and engaged with first lock member 30.

Thereafter, when the engine speed enters an idling operation of about 900 rpm, the centrifugal force of housing 5 increases, and forces the second lock member 33 backwards into second slide hole 32 by compressing the second spring 34 gradually as shown in FIG. 8. Consequently, the first and second lock members 30 and 33 are disengaged from each other, and the lock mechanism is brought to the unlock state allowing vane member 3 to rotate. However, vane member 3 is held at the most retarded position shown in FIG. 8 by the continuation of supply of hydraulic pressure to retard chambers 18.

When the engine speed increases from the low speed low load region above, 900 rpm to the medium speed medium load region, the directional control valve 23 is switched by controller 26 to the state to supply the hydraulic pressure to the advance chambers 17 instead of the retard chambers 18, so the hydraulic pressure in retard chamber 18 decreases and the hydraulic pressure in advance chambers 17 increases. Therefore, first lock member 30 moves backwards into first slide hole 29 by the hydraulic pressure of the advance chambers 17 acting on the forward end portion 30 a, and vane member 3 rotates in the clockwise direction as viewed in FIG. 8 or the advance direction, from the most retarded position of FIG. 8, to an intermediate position or to the most advanced position. Thus, camshaft 2 is rotated in the advance direction with respect to timing sprocket member 1, and the same effects as in the first embodiment can be obtained.

In this state, second lock member 33 receives the centrifugal force. However, the hydraulic pressure supplied to advance chamber 17 is introduced to the inside of second lock member 33 through the through hole 38. This hydraulic pressure acts on the relatively large pressure receiving area inside second lock member 33, and the resulting force of this pressure and the spring force of second spring 34 becomes greater than the centrifugal force, and pushes the second lock member 33 forwards into the projected position as shown in FIGS. 9 and 10.

Thus, in the second embodiment, by utilizing the centrifugal force to move second lock member 33 backwards, the lock mechanism is simplified to the advantage of cost reduction.

FIG. 11 shows a valve timing control apparatus according to a third embodiment of the present invention. The hydraulic circuit 4 including the solenoid direction control valve 23 is constructed in the same manner as in the first embodiment, for supplying the hydraulic pressure to advance chambers 17 and retard chambers 18. In addition to this hydraulic circuit section for supplying the hydraulic pressure selectively to the advance and retard chambers 17 and 18, the hydraulic section of the valve timing control apparatus according to the third embodiment further includes a hydraulic circuit section for supplying the hydraulic pressure to the pressure chamber 33 b of second slide hole 34.

On the downstream side of the oil pump 25, there is provided a third fluid pressure passage 42 having one end opening into the pressure chamber 33 b. A second solenoid direction control (or selector) valve 43 is arranged to connected the third pressure passage 42 selectively with a supply passage 44 connected to the downstream side of the oil pump 25, and a drain passage 45 connected to the oil pan 24.

With the circuit section including second control valve 43 for controlling the fluid pressure in the pressure chamber 33 b independently from the fluid pressures in the advance and retard chambers 17 and 18, the valve timing control system according to the third embodiment can move the second lock member 33 forwards and backwards quickly by supplying and draining the hydraulic pressure directly to and from the pressure chamber 33 b. Thus, the locking and unlocking operations of first and second lock members 30 and 33 are quick, and the response in the valve timing control is improved.

FIGS. 12˜15 show a valve timing control apparatus or system according to a fourth embodiment of the present invention. In the fourth embodiment, the first and second lock members 30 and 33 are in the form of a pin. In this embodiment, the first and second lock members or lock pins 30 and 33 are identical in size and shape. Each of first and second lock pins 30 and 33 includes a flange or slide portion 30 c or 33 c formed integrally at the back end of the pin.

Slide holes 29 and 32 are formed so that the axes of slide holes 29 and 32 overlap each other in the circumferential direction of vane member 3. Each slide hole 29 or 32 includes a front small diameter section, a rear large diameter section, and a step shoulder surface 29 a or 32 a formed between the small and large diameter sections. The flange 30 c or 33 c of each lock pin 30 or 33 is slidably received in the rear large diameter section of the corresponding slide hole 29 or 32. The step shoulder surface 29 a or 32 a of each slide hole 29 or 32 faces backwards toward the bottom of the slide hole, and limits the forward movement of the corresponding lock member 30 or 33 by abutting against the flange 30 c or 33 c of the lock pin, thereby to determine the most projected position of the lock member.

At the most retarded position as shown in FIG. 12, the forward portions of first and second lock pins 30 and 33 abut against each other, and thereby the first and second lock pins 30 and 33 prevent rotation of vane member 3 in the clockwise (advance) direction as viewed in FIG. 12. On the other hand, the vane 15 having the greatest circumferential width L3 abuts on the adjacent partition 10. Therefore, the vane member 3 is held at the most retarded position.

First and second springs 31 and 34 are set small relatively in diameter. A back end portion of first spring 31 is received in a spring retaining hole formed in the bottom of first slide hole 29. A back end portion of second spring 34 is received in a spring retaining hole formed in a cover member or plug member 40 closing the back end of the second slide hole 32. In the other respects, the third embodiment is substantially identical in construction to the first embodiment.

In an engine starting operation, the first lock pin 30 abuts against second lock pin 33 as shown in FIG. 12 and thereby prevents rotation of vane member 3. In an idling operation, the hydraulic pressure supplied from retard chambers 18 to the pressure chamber 33 b is still low. Therefore, though second lock pin 33 is retracted backwards slightly as shown in FIG. 13, the first and second lock pins 30 and 33 are held engaged.

When the engine speed is further increased, and the engine operating point enters the low speed low load region, the solenoid valve 23 is switched to the state supplying the hydraulic pressure to advance chambers 17, and the pressure in advance chambers 17 become high. Therefore, as shown in FIG. 14, first lock pin 30 is retracted backwards in first slide hole 29 by the hydraulic pressure acting on the forward end of first lock pin 30, and thereby disengaged from second lock pin 33; and the vane member 3 is rotated in the advance (clockwise) direction by the hydraulic pressure in advance chambers 17. In a medium speed high load region, for example, the hydraulic pressure in advance chambers 17 is further increased, and the vane member 3 is held at the most advanced position at which the vane 15 having the greatest circumferential width L3 abuts on the adjacent partition 10.

In the high speed high load region, the operating oil is drained from advance chambers 17 and the vane member 3 is rotated in the retard (counterclockwise) direction. However, immediately after this switching operation, the hydraulic pressure is supplied to retard chambers 18 and the hydraulic pressure in advance chambers 17 is not abruptly decreased. Therefore, first lock pin 30 is not projected so much, and second lock pin 33 is slightly retracted, so that the vane member 3 can rotate to the most retarded position without interference between first and second lock pins 30 and 33.

In the fourth embodiment, the first and second lock members 30 and 33 are identical to each other, so that the manufacturing cost can be reduced. The valve timing control apparatus according to the fourth embodiment can improve the fuel consumption and other engine performance as in the preceding embodiments.

FIGS. 16 and 17 show a valve timing control apparatus or system according to a fifth embodiment of the present invention. In the fifth embodiment, first and second lock members 30 and 33 are arranged in the axial direction instead of the radial direction.

An axial first slide hole 29 is formed in the vane 15 having a larger circumferential width. First slide hole 29 extends in the axial direction along the center axis of vane member 3. First slide hole 29 is a stepped hole having a larger section and a smaller section having a cross sectional size smaller than the cross sectional size of the larger section. An axial second slide hole 32 is formed in a thick wall portion of rear plate 7 of timing sprocket member 1 at a position confronting the first slide hole when vane member 3 is at a predetermined (most retarded) rotational position. Second slide hole 32 extends in the axial direction along the common center axis of vane member 3 and timing sprocket member 1. A back end of second slide hole 32 is closed by a cover or plug member 40. Cover member 40 is shaped like a thin circular disk, and fixed to rear plate 7 so as to form the bottom of second slide hole 32. An air release hole is formed approximately at the center of cover member 40 to ensure smooth movement of second lock member 33 in second slide hole 32.

First lock member 30 is a cup-shaped member including a cylindrical wall extending from a backward end to a forward end toward rear cover 7, and a forward end portion 30 a closing the forward end of the cylindrical wall. Second lock member 33 is a cup-shaped member including a cylindrical wall extending from a backward end to a forward end toward front cover 6, and a forward end portion closing the forward end of the cylindrical wall. First lock member 30 is slidably received in first slide hole 29 so that first lock member 30 can move forwards and backwards in the axial direction. Second lock member 33 is slidably received in second slide hole 32 so that second lock member 33 can move forwards and backwards in the axial direction.

The forward end portion 30 a of first lock member 30 is formed with a (lock) projection which is a cylindrical projection projected axially, in this example. First lock member 30 further includes an outward flange formed integrally at the backward end and arranged to abut on a step 29 c formed in first slide hole 29 to limit the forward movement of first lock member 30.

The forward end portion of second lock member 33 is formed with a (lock) recess 37 in which the projection formed in forward end portion 30 a of first lock member 30 can be fit loosely. Recess 37 of FIG. 16 is axially depressed. The outside surface of cylindrical wall of second lock member 33 is stepped, and there is formed an annular step shoulder surface 33 receiving the hydraulic pressure in an annular pressure chamber 33 b formed around second lock member 33. The pressure receiving area of the annular step shoulder surface 33 is set at an appropriate value.

A communication passage 36 extends from one of retard chambers 18 to the annular pressure chamber 33 b to supply the hydraulic pressure from the retard chamber 18 to pressure chamber 33 b. In the other respects, the fifth embodiment is substantially identical to the first embodiment.

Therefore, the fifth embodiment can provide the same effects as the first embodiment. In an engine starting operation, the hydraulic pressure in annular pressure chamber 33 b is not increased yet, and the second lock member 33 is held engaged with first lock member 30. In an idling operation, the hydraulic pressure supplied in pressure chamber 33 b is slightly increased, and second lock member 33 is retracted backwards and disengaged from first lock member. However, the hydraulic pressure is still insufficient, and the vane member 3 is held at the most retarded position.

When, for example, the engine speed is increased from the low speed low load region to the medium speed high load region, the solenoid valve 23 is switched to the state supplying the hydraulic pressure to advance chambers 17, and the vane member 3 is rotated in the advance (clockwise) direction by the hydraulic pressure in advance chambers 17. Thus, the valve timing control system can improve the engine performance sufficiently as in the first embodiment.

In the fifth embodiment, first and second lock members 30 and 33 are arranged axially along the axis of camshaft 2. Therefore, the lock mechanism receives no influence of the centrifugal force of housing 5, and the first and second lock members 30 and 33 can be moved only by the hydraulic pressures. Thus, the fifth embodiment can improve the control response to control the relative rotation between timing sprocket member 1 and camshaft 2.

The present invention is not limited to the illustrated embodiments. Various variations and modifications are possible. For example, instead of the timing sprocket member 1, the driving member may be a timing pulley driven through a timing belt of rubber. This arrangement is advantageous for reduction of vibrations and noises.

Moreover, the driving member may be a gear member driven by a gear mechanism transmitting motion by a combination of two or more gears. In this case, the driving force can be transmitted securely. Furthermore, as the gear mechanism, it is possible to employ scissors gear to reduce backlash noises.

The valve timing control actuator may be a helical type VTC actuator, instead of the vane type VTC actuator. In the helical type, the relative rotational phase is shifted with axial movement of a tubular toothed member.

The valve timing control actuator may be electric or electromagnetic, instead of the hydraulic actuator. In this case, the relative rotational phase between the driving and driven members is altered by an electric device such as an electric motor or an electromagnetic brake.

It is sufficient to provide only one pair of the advance fluid pressure chamber and retard fluid pressure chamber. The number of pairs of the advance and retard chambers may be one, or may be two, three or four or more. When the number of pairs is increased especially in the case of the vane type VTC actuator, the pressure receiving areas are increased, and the response characteristic of the VTC actuator is improved.

It is not always necessary to dispose the first and second movable members in one of the advance and retard fluid pressure chambers. The first and second movable members may be placed at a position separate from the advance and retard chambers.

The first and second movable members may be placed at various portions of the driving and driven rotary members which are arranged to rotate relative to each other. The first and second movable members need not be placed between a member, such as a sprocket, driven directly by a crankshaft, and a member, such as a vane member, driving directly a camshaft. At least one of the first and second movable members may be mounted in a member (such as the above-mentioned tubular toothed member of the helical VTC actuator) interposed between the member directly driven by the crankshaft and the member directly driving the camshaft.

The first and second movable member may be shaped in various forms. Either or both of the first and second movable members may be in the form of a cylindrical pin, a polygonal pin polygonal in cross section, a ring-shaped member, or a plate-shaped member, or in the form of a lever.

Instead of the engagement between the (lock) recess 37 and the (lock) projection like tenon and mortise, it is possible to employ various forms for abutting portions of first and second movable members. When the relative rotation of the rotary mechanism of driving rotary member and driven rotary member is limited within a predetermined range, it is possible to arrange the first and second movable members to prevent the relative rotation between the driving and driven members only in one direction by abutment between the first and second movable members in the circumferential direction, and to prevent the relative rotation in the opposite direction by the rotary mechanism of the driving and driven members.

Instead of a coil spring, it is possible to employ, as at least one of the first and second bias members, a leaf spring or a disk spring. The directions of forward and backward movement of the first and second movable members are not limited to the radial direction and the axial direction. It is possible to employ various directions as the directions of the first and second movable members.

Instead of the tapered or conical surface around the recess 37, it is possible to employ various forms of the guide portion for guiding the first and second movable member into engagement or into the lock state. For example, a tapered surface may be formed around the projection of one movable member to be engaged in the recess of the other movable member. Moreover, it is possible to form a tapered surface only in a part of the circumference of the recess 37. In this case, the movable member formed with the recess is arranged so that the rotation about its own axis is limited or prevented. Furthermore, it is possible to employ, as the guide portion or guide means, a mechanism using one or more links, or a cam mechanism or other shaped portion or device for moving at least one of the first and second movable members backwards by using a relative rotation between the driving and driven rotary members, or translating a relative rotation between the driving and driven rotary members into a linear motion of at least one of the first and second movable members.

One of the first and second movable members is a first released member which is first moved backwards first by the application of a hydraulic pressure when the engine is started. In the first embodiment, for example, the second lock member is the first released member which is first acted upon by the application of the retard fluid pressure after the engine is started. At least the bias member (such as second spring 34) of the first release member (such as second lock member 32) is so set that the bias member can hold the first release member in the projected position to prevent the relative rotation between the driving rotary member and driven rotary member when an air pressure is applied to the first release member and that the bias member allows the first release member to be moved backwards when a hydraulic pressure is applied. Moreover, the bias member (such as second spring 34) of the first release member (such as second lock member 32) is so set that the biasing force or spring force of the first release member is greater than that of the other bias member.

This application is based on a prior Japanese Patent Application No. 2005-143354 filed on May 17, 2005. The entire contents of this Japanese Patent Application No. 2005-143354 are hereby incorporated by reference.

Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. The scope of the invention is defined with reference to the following claims. 

1. A valve timing control apparatus for an internal combustion engine, comprising: a driving rotary member adapted to be driven by the engine; a driven rotary member arranged to rotate relative to the driving rotary member and adapted to rotate a camshaft of the engine; a first movable member provided in a first rotary member, and arranged to move forwards and backwards, the first rotary member being one of the driving rotary member and the driven rotary member; and a second movable member provided in a second rotary member and arranged to move forwards and backwards, the second rotary member being the other of the driving rotary member and the driven rotary member, the first and second movable members being arranged to limit a relative rotation between the driving rotary member and the driven rotary member when both the first movable member and the second movable member are moved forwards, and to allow the relative rotation between the driving rotary member and the driven rotary member when at least one of the first and second movable members is moved backwards.
 2. The valve timing control apparatus as claimed in claim 1, wherein the driving rotary member is adapted to be driven by a crankshaft of the engine; the driven rotary member is adapted to rotate as a unit with the camshaft; and the valve timing control apparatus further comprises: a first bias member arranged to bias the first movable member forwards toward the second rotary member; a second bias member arranged to bias the second movable member forwards toward the first rotary member; and a control section to alter a relative rotational position of the driven rotary member relative to the driving rotary member.
 3. The valve timing control apparatus as claimed in claim 1, wherein the valve timing control apparatus further comprises a first bias member arranged to bias the first movable member to move the first movable member forwards toward the second movable member, and a second bias member arranged to bias the second movable member to move the second movable member forwards toward the first movable member; and wherein the first movable member and second movable member are arranged to abut against each other to limit the relative rotation between the driving rotary member and the driven rotary member when the first and second movable members are projected forwards.
 4. The valve timing control apparatus as claimed in claim 3, wherein the valve timing control apparatus further comprises an actuating device to force at least one of the first and second movable members backwards to allow the relative rotation between the driving rotary member and the driven rotary member.
 5. The valve timing control apparatus as claimed in claim 3, wherein the first and second movable members are so arranged that the first and second movable members are moved forwards to limit the relative rotation between the driving rotary member and the driven rotary member at the time of start of the engine, and that at least one of the first and second movable members is moved backwards to allow the relative rotation between the driving rotary member and the driven rotary member after the start of the engine.
 6. The valve timing control apparatus as claimed in claim 3: wherein the driving rotary member and the driven rotary member are arranged to define an advance fluid pressure chamber to rotate the driven rotary member in an advance direction relative to the driving rotary member when an advance fluid pressure is supplied to the advance fluid pressure chamber, and a retard fluid pressure chamber to rotate the driven rotary member in a retard direction relative to the driving member when a retard fluid pressure is supplied to the retard fluid pressure chamber; and wherein at least one of the first and second movable members is arranged to move backwards in accordance with one of the advance fluid pressure and the retard fluid pressure.
 7. The valve timing control apparatus as claimed in claim 6, wherein the driven rotary member includes a vane projecting radially outwards and separating the advance fluid pressure chamber and the retard fluid pressure chamber; and the driving rotary member enclosing the driven rotary member and defining the advance and retard fluid pressure chambers between the driving rotary member and the driven rotary member.
 8. The valve timing control apparatus as claimed in claim 6, wherein at least one of the first and second movable members is bared in one of the advance fluid pressure chamber and the retard fluid pressure chamber to move backwards in accordance with one of the advance fluid pressure and the retard fluid pressure.
 9. The valve timing control apparatus as claimed in claim 6, wherein at least one of the driving rotary member and the driven rotary member is formed with a communication passage to convey one of the advance fluid pressure and the retard fluid pressure to move one of the first and second movable members backwards.
 10. The valve timing control apparatus as claimed in claim 6, wherein the first movable member is arranged to move backwards in accordance with the advance fluid pressure against a biasing force of the first bias member; and the second movable member is arranged to move backwards in accordance with the retard fluid pressure against a biasing force of the second bias member.
 11. The valve timing control apparatus as claimed in claim 6, wherein the first movable member is arranged to move backwards in accordance with one of the advance fluid pressure and the retard fluid pressure against a biasing force of the first bias member; and the second movable member is arranged to move backwards in a radial outward direction by a centrifugal force.
 12. The valve timing control apparatus as claimed in claim 6, wherein the first and second movable members are both exposed to a hydraulic pressure in one of the advance fluid pressure chamber and the retard fluid pressure chamber; and the first movable member is arranged to be forced backwards by the hydraulic pressure whereas the second movable member is not forced by the hydraulic pressure.
 13. The valve timing control apparatus as claimed in claim 12, wherein the first movable member includes a forward end portion arranged to receive the hydraulic pressure only on a forward side to be pushed backwards by the hydraulic pressure; and the second movable member includes a forward end portionformed with a through hole so that the second movable member receives the hydraulic pressure on both of a forward side and a back side of the second movable member.
 14. The valve timing control apparatus as claimed in claim 6, wherein one of the first and second movable members includes an outside circumferential surface and a pressure receiving outward flange surface which projects outwards from the outside circumferential surface and which is arranged to receive one of the advance fluid pressure and the retard fluid pressure.
 15. The valve timing control apparatus as claimed in claim 14, wherein the second movable member includes the pressure receiving outward flange surface which is annular; and the second rotary member includes a portion defining an annular pressure chamber which is formed around the second movable member, and which is connected with one of the advance fluid pressure chamber and the retard fluid pressure chamber.
 16. The valve timing control apparatus as claimed in claim 3, wherein one of the first and second movable members includes a projection and the other of the first and second movable members includes a recess to receive the projection to limit the relative rotation between the driving and driven rotary members when the first and second movable members are moved forwards toward each other.
 17. The valve timing control apparatus as claimed in claim 3, wherein the first rotary member includes a support portion supporting the first movable member and allowing the first movable member to move radially around an axis of the camshaft; and the second rotary member includes a support portion supporting the second movable member and allowing the second movable member to move radially around the axis of the camshaft.
 18. The valve timing control apparatus as claimed in claim 3, wherein the first rotary member includes a support portion supporting the first movable member and allowing the first movable member to move axially along an axis of the camshaft; and the second rotary member includes a support portion supporting the second movable member and allowing the second movable member to move axially along the axis of the camshaft.
 19. The valve timing control apparatus as claimed in claim 1, wherein the first and second movable member are arranged to move into a lock state to prevent the relative rotation between the driving and driven rotary members when the driven member is at a predetermined first rotational position relative to the driving member, and at least one of the first and second movable members is arranged to be moved backwards by a relative rotation of the driven member relative to the driving member from a second rotational position away from the predetermined first rotational position, to the predetermined first rotational position.
 20. The valve timing control apparatus as claimed in claim 19, wherein the valve timing control apparatus further comprises a guide portion to guide the first and second movable members into the lock state when the driven rotary member rotates from a rotational position away from the first rotational position, to the first rotational position relative to the driving member with at least one of the first and second movable members being projected forwards.
 21. The valve timing control apparatus as claimed in claim 20, wherein the guide portion is arranged to guide the first and second movable members into the lock state by receiving an operating force produced when the crankshaft of the engine is rotating.
 22. The valve timing control apparatus as claimed in claim 19, wherein one of the first and second movable members is formed with a guide portion to guide the first and second movable members into the lock state when the driven rotary member rotates from a rotational position away from the first rotational position, to the first rotational position relative to the driving member.
 23. The valve timing control apparatus as claimed in claim 19, wherein the first and second movable members includes, respectively, first and second abutting portions which are arranged to abut against each other when the driven rotary member rotates from a rotational position away from the first rotational position toward the first rotational position relative to the driving member with the first and second movable members are projected forwards; and at least one of the first and second abutting portions includes an inclined surface to guide the first and second movable members into the lock position.
 24. The valve timing control apparatus as claimed in claim 23, wherein one of the first and second abutting portions includes the inclined surface which is a tapered surface, and the other of the first and second abutting portions includes a non-tapered surface abutting on the tapered surface.
 25. The valve timing control apparatus as claimed in claim 2, wherein the valve timing control apparatus further comprises a control section to alter a rotational position of the driven rotary member relative to the driving rotary member.
 26. The valve timing control apparatus as claimed in claim 25, wherein the control section includes a hydraulic section to rotate the driven rotary member in an advance direction relative to the driving rotary member by supplying an advance fluid pressure to an advance chamber, and to rotate the driven rotary member in a retard direction relative to the driving rotary member by supplying a retard fluid pressure to a retard chamber; the first movable member is arranged to move backwards in accordance with the advance fluid pressure against a biasing force of the first bias member; and the second movable member is arranged to move backwards in accordance with the retard fluid pressure against a biasing force of the first bias member.
 27. The valve timing control apparatus as claimed in claim 26, wherein one of the first and second bias members is a spring so set as to allow the movable member biased by the spring, to move backwards when a hydraulic pressure is applied the movable member biased by the spring, and as to prevent a backward movement of the movable member biased by the spring when a pressure of air is applied; and wherein the movable member biased, by the spring is acted upon by a hydraulic pressure which is one of the advance fluid pressure and the retard fluid pressure and which is supplied to a corresponding one of the advance fluid chamber and the retard fluid chamber first after the engine is started.
 28. The valve timing control apparatus as claimed in claim 26, wherein one of the first and second bias members is a greater bias member having a biasing force greater than a biasing force of the other of the first and second bias members; and wherein the movable member biased by the greater bias member is acted upon by a hydraulic pressure which is one of the advance fluid pressure and the retard fluid pressure and which is supplied to a corresponding one of the advance fluid chamber and the retard fluid chamber first after the engine is started.
 29. The valve timing control apparatus as claimed in claim 25, wherein the control section includes a controller to cause the first and second movable members to move forwards to limit the relative rotation between the driving rotary member and the driven rotary member at the time of start of the engine, and to cause at least one of the first and second movable members to be moved backwards to allow the relative rotation between the driving rotary member and the driven rotary member after the start of the engine.
 30. The valve timing control apparatus as claimed in claim 3, wherein the first movable member is arranged to move backwards against a biasing force of the first bias member in accordance with a fluid pressure produced by a fluid pump driven by the engine; and the second movable member is arranged to move backwards against a biasing force of the first bias member in accordance with a fluid pressure produced by the fluid pump.
 31. An internal combustion engine comprising: a crankshaft; a camshaft; a valve timing control rotary mechanism including, a driving rotary member driven by the crankshaft of the engine, and a driven rotary member) which is arranged to be driven by the driving rotary member and to drive the camshaft, and which is arranged to rotate relative to the driving rotary member to alter a rotational position of the driven rotary member relative to the driving rotary member; and a lock mechanism including, a first movable member mounted in the driven rotary member and arranged to move forwards toward the driving rotary member and backwards away from the driving rotary member, and a second movable member mounted in the driving rotary member and arranged to move forwards toward the driven rotary member and backwards away from the driven rotary member, the second movable member being arranged to abut against the first movable member and thereby to limit a relative rotation between the driving rotary member and the driven rotary member when both the first movable member and the second movable member are moved forwards. 